Removable artificial dental crown.



w. E. CHESTER. REMOVABLE ARTIFICIAL DENTAL CROWN.

APPLICATION FILED MAY 3, 19H).

Patented Jan. 23, 1917.

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WILLIAIVI E.

CHESTER, OF NORWOGD,

OHIO.

REMOVABLE ARTIFICIAL DENTAL CROWN.

Application filed May 3,1916.

To all whom it may concern:

Be it known that I, EVILLIAM E. CHESTER, acitizen of the United States of America, and a resident of Norwood, in the county of Hamilton and State of Ohio, have invented certain new and useful Improvements in -Removable Artificial Dental Crowns, of which the following is a specification.

This invention relates to improvements in artificial teeth, or, more particularly speaking, to removable or replaceable crowns, caps or facings for the roots of teeth that are left or retained in place and from which, as a rule, the nerves have been removed or other wise deadened.

The objects of the invention herein will be fully set forth in connection with the description of the details thereof that imme- .diately follows that of the accompanying sheet of drawings, in which latter,

Figure 1 is a rear elevation showing the natural root of a tooth with a surmounted artificial crown or cap, the latter being in :emovable-place according to my preferred form herein; Fig. 2, a vertical axial-section of Fig. 1, but on a slightly larger scale and showing my improved fastening-connections between the tooth root and its artificial crown or cap; Fig. 3, a plan view of the root, taken on the line a, a, of Fig. 2, but omitting the improved connecting post or pin that I use between the said root and the crown; Fig. 4, an elevation showing one form of my improved doubly-shouldered connecting post or pin and omitting the boxing therefor that is shown in Fig. 2; Fig. 5, a plan of the post seen in Fig. 4; Fig. 6, an elevation showing a modified form of the post or pin seen in Fig. l; Fig. 7, a front elevation of a wire frame or reinforce that is shown in the crown-portion of the tooth in Fig. 2, but with the crown-portion omitted; and Fig. 8, plan view of the reinforce shown in Fig. 7.

It will be observed, before proceeding further, that the several views of the drawings are made on an exceedingly exaggerated scale over and above the actual size of the several parts that form the essential features of the invention herein.

1 indicates the natural tooth root sur-' mounted by the crown or cap 2, the two being connected together by means of my preferred form of post or pin composed of a cylindrical body-portion 3 that has a lower,

Specification of Letters Patent.

Patented Jan. 23, 191%.

Serial No. 85,258.

tapered point 4t, a head-portion 5 that has a flange 6 and a surmount-mg shoulderedpart '7, the latter being of lesser diameter than the flan e 6, and an upper, sligl'itly tapered shank 9 of rectangular cross-section. The base of shank 9 is of lesser diameter than the part 7 to produce a shoulder 10 on said part 7.

. 1 indicates the customary pulp or nerve canal of the root 1.

The upper part of the pulp-canal 11 is suitably drilled out to produce the special form of seat or expanded, shouldered chamher in the upper end thereof, as best seen in Fig. 2, whereby a lower shoulder 16 is made at the bottom of said seat and extends upwardly, and is screw-threaded as shown at 17, thence expands into a broad shoulder 18 having at its outer edge a groove 19, the face of the shoulder 18 being somewhat below the upper face of the root 1. In this seat or countersunk-recess, made in the upper part of the pulp-canal, I provide a metallic box or bushing that has a body-portion 20 resting upon the grooved shoulder 18 and a lower, screw-threaded cylindricalportion 21 that engages the shouldered, screw-threaded portion 16, 17 of said seat. A tapered plug 22 is used in the said screwthreaded portion 1'? of the box or bushing to fasten the latter in place in said upper seat of the root. This bushing is intended to prevent the splitting of the root as well as to serve as a support for the said removable post. The internal diameter of said bushing is made to coincide with that of the post 3, so that the latter can be inserted and tightly held therein and that it can be readily removed from the root when it is desired to get at the pulp-canal, down to the bottom thereof, and even beyond, if necessary, for the treatment of abscesses or other ailments.

A lug or projection 23 is provided on the flange 6 and engages a notch 24 made in the upper shouldered portion 25 of the bushing, as best shown in Figs. 2 and 3, a vertical screw 27 being inserted through a countersunk opening made in said lug 23 and adapted to engage a threaded hole made in the body-portion of said bushing, whereby the post 3 can be securely held within said bushing against turning or accidental withdrawal, but detachable. Instead of using the said bushing the post 3 can be inserted in the upper portion of the pulp-canal, after the latter has been duly prepared therefor,

a shouldered recess being provided in the upper end or mouth of said pulp-canal, as shown in Figs. 4: and 6, to accommodate the flange-portion 6 its full depth, as seen in L, or half the depth of the singleshouldered bro-ad flange 7 seen in Fig. 6. In Fig. & the post 3 is shown as a plain one, while in Fig. 6 it is shown as a threaded one, the latter being adapted to engage a suitably threaded upper part of the pulpcanal for the due fastening thereof, while the plain post is preferably held in place by any easy drive-fit or a thin film of cement used therefor. The thin film used on the post 3 seen in Fig. i would not ordinarily be adhesive enough to prevent the removal of the post from the pulp-canal, because it is intended by me that the post can be removed by the dentist when it is desired to remove the crown or cap for any purpose and especially when it is necessary to get into the pulp-canal or at the base of the root.

If desired the lug 23 on the flange 6 and its recess 2% in the box can be dispensed with and the post held within the box or brushing by an internal thread in the latter, in which case the said post must be threaded, as shown in Fig. 6.

The crown or cap 2 is preferably held in place on the shank 9 in a detachable manner by means of a horizontal screw 29 whose inner end engages a seat made in said shank, as best shown in Fig. 2. The head of said screw 29 is made to seat flush with the inner face or lingual side of said crown and the threaded shank of the screw engages the internally threaded portion of a metal lining or bushing 30, at whose inner end a vertical, cylindrical member 31 is provided to engage over said'shank 9, with its lower end resting on the shouldered portion 7 of the post, whereby the crown is securely held on said post with its base resting in true and flush contact with the upper dressed face of the root 1, entirely free from vibration, rocking, or wabbling. The shank 9 of the post may be made either tapering or straight, as desired.

In order to preserve the artificial or porcelain crown 2 from fracturing or breaking under ordinary conditions, I provide a reinforcing skeleton-frame that is embedded within the porcelain or material of said crown, as best shown in Fig. 2, but the reinforce is well shown in Figs. 7 and 8, wherein 32, 32 indicate vertical strips or bars, and 33, 34 indicate transverse strips or bars that are made of wire and somewhat roughened for better embedding-engage. nient withthe substanceof said crown.

It will be observed in Fig. 4 that the shank 9 is a tapered and angular'one, while in Fig. 6 the shank is also made tapered but crown in supported-position on round, both forms being adapted for use in connection with my improved doublyshouldered post or pin, the angular form preventing the turning of the post after the shank has once been set in place in the bushing 31, while the round form is peculiarly adapted to the screw-threaded form of post 3 seen in said Fig. 6 and to a circular bushing instead of the square bushing shown in Figs. 5 and 8.

It will be seen from the above description that the principal feature of my invention resides in preventing the splitting of the root, and the ready accessibility to the pulp or nerve canal that may be easily reached by simply removing the screw 29 to release the crown or cap 2, and then removing the screw 27 so that the improved doublyshouldered post can be withdrawn from the upper end of said pulp or nerve canal. The crown can be just as readily replaced by the reverse handling of said post and screws.

.1 claim 1. In combination, a dental crown or cap, a tooth root, a fastening or coupling intervening said crown and root and comprising a vertical post having a body-portion' adapted to removably-extend into the pulpcanal of the root, a doubly-shouldered head or flange on said body-portion adapted to removably seat in a shouldered recess made in the upper end of said pulp-canal, a vertical shank on said head adapted to engage a pit provided in the bottom of the crown, and means in the crown adapted to removably-fasten it to said shank in firm, upright position on the top of the root.

2. In combination, a dental crown or cap, a tooth root, a fastening or coupling intervening said crown and root and comprising a vertical post having a pointed body-portion adapted to removably-engagethe pulp canal of the root, a doubly-shouldered head or flange on said body-portion adapted to partially and removably seat in a shouldered crown adapted to engage said shank, and a transverse screw inserted into the crown from its lingual side and adapted to engage the said shank for removably-fastening the the top or finished table of said root.

3. In combination, a dental crown or cap, a tooth root,'a vertical doublyshouldered post or pin adapted to removably-engage the pillp canal in the tooth root, a doublyshouldered and grooved seat inthe upper end of said pulp-canal, a flanged metal box or bushing fitting within said doubly-shouldered and'grooved seat and adapted to contain theshouldered-portion of the post, a

lateral 'lug' on said doubly-shouldered pertion of the post adapted to engage a notch countersunk screw in said lateral lining for made in the countersunk upper portion of removably-fastening or mounting the crown the box or bushing and to receive a veron the said shank and the root top.

tical fastening-screw, an upright shank on W'ILLIAM E. CHESTER. the post, a vertical box or bushing in the Witnesses:

crown to engage said shank and provided JOHN ELIAS JONES,

with a lateral threaded box or lining, and a BERL R. DAVIS.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. Q. 

